1. Field of the Invention
The invention is generally related to the area of optical information recording medium. More particularly, the present is related to bubble-free techniques for bonding substrates and minimizing possible dynamic imbalance.
2. The Background of Related Art
One of the most popular optical storage medium is DVD (Digital Versatile Disc). Technically, DVD is a relatively new generation of optical disc storage technology. It is much larger in data capacity and faster in reading than CD and can hold cinema-like video, better-than-CD audio, still photos, and computer data. DVD aims to encompass home entertainment, computers, and business information with a single digital format. It has replaced laserdisc, is well on the way to replacing videotape and video game cartridges, and could eventually replace audio CD and CD-ROM. DVD has widespread support from all major electronics companies, all major computer hardware companies, and all major movie and music studios. With this unprecedented support, DVD became the most successful storage device of all time in the history of optical storage technologies.
Although blank or content DVD manufacturing is similar to CD manufacturing in that mastering, electroforming (stamper making), molding, metalizing, printing, and testing are required, there are significant differences that include bonding two circular substrates together, additional testing, and the handling of much smaller physical features and specifications. Each of steps in manufacturing DVD requires significant attention in order to increase the product yield and manufacturing speed and, at the same time, reduce the manufacturing costs.
Bonding, for example, is the most sensitive step of the DVD manufacturing process. The importance of this step can not be overemphasized. Improper bonding can create discs that are warped, unbalanced, improperly aligned, have bubbles, etc., all leading to out-of-specification discs that would not be played at the speed required for many applications such as movies and video games. At the very least, trouble in this area could lead to lower production yields and ultimately higher costs and slower delivery. There have been many efforts in bonding techniques to improve the DVD manufacturing process. However, current solutions are not satisfactory, inferior DVD resulted from the bonding step alone can be noticed that the production yield is being diluted.
Therefore there has been a great need for techniques that produce disk-shaped optical medium with minimum errors, improve production speed and reduce costs of the optical medium that can be subsequently read at substantially high speeds with greater stability and accuracy.